Apparatus for pulping paper stock



July 10, 1962 Filed Aug. 29, 1958 E. COWLES APPARATUS FOR PULPING PAPERSTOCK 3 Sheets-Sheet l INVENTOR. EDW COVVZE'S' BY 7 .2mm PM ATTORNEYSJuly 10, 1962 E. cowLEs 3,043,526

APPARATUS FOR PULPING PAPER STOCK Filed Aug. 29, 1958 3 Sheets-Sheet 2Fig. 3. 24 2Q 4 Hl 1 a 23 Q J 7 l l 43 41 I l 32 4,7 45 39 I 3 I 1}: 51I m .37 :L

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INVENTOR. Epmzv C'OI/VLES BY PM PM ATTORNEYS ly 10, 1962 E. cowLEs3,043,526

APPARATUS FOR PULPING PAPER STOCK Filed Aug. 29, 1958 3 Sheets-Sheet 3 F6. 62 INVENTOR.

' i EDWIN cowzEs I BY 7 .2mm *TWM ATTORNEY/S 3,l43,526 APPTUS F0112PULPING PAPER STQCK Edwin Cowles, New York, N.Y., assignor to John W.Bolton & Sons, lnc., Lawrence, Mass., a corporation of MassachusettsFiled Aug. 29, 1%8, Ser. No. 758,097 9 Claims. (Cl. 241-46) Thisinvention relates to an apparatus for pulping paper stock including themaking of paper stock from waste paper, virgin pulp and the like. i

The invention pertains to machines of the general type illustrated in myprior Patents 2,351,492 and 2,557,174 wherein an impeller rotates on avertical axis in the bottom of a tank to create a vortex in the paperstock while discharging stock from the periphery of the impeller,thereby circulating and pulping the paper stock.

It has heretofore been proposed to mount such an impeller in a volutechamber at one end of a midfeathered, Hollander type, beater theperipheral discharge from the impeller being directed up and around theparallel reaches of the beater until the stock cascades down into theimpeller casing.

I have found that in such a relatively shallow tank with large area thevortex which forms is so large that the pulping and defibering action isimpaired. The solution to this problem is to use a deeper tank, havingless area which also improves the circulation and dumpingcharacteristics of such machines while retaining sufiicient vortexingaction for efiicient submergence of floating materials.

l have found that a tank of considerable area such as -a Hollander typebeater requires an impeller of considerable area to maintain a goodvertical action which will submerge floating material in the paperstock. Such large diameter impellers require substantial horse power tomaintain the desired peripheral speed and at the desired peripheralspeed the stock tends to spill over the sides of the tank.

The principal object of this invention is to provide a tank in whichgood vortical circulation may be maintained by a relatively smalldiameter impeller, the volume of the tank being large because of itshigh side wall rather than because of the area of the tank bottom.

Another object of the invention is to provide a deep tank of ovateconfiguration with a relatively small diameter impeller in one endthereof whereby the other end of the tank contains a large mass ofmaterial close enough to the pumping effect of the impeller to bereadily affected thereby.

A further obiect of the invention is to provide a pulping apparatuswhereby the paper stock material is continually subjected to the actionof an impeller by the combined effect of lopsided vortical circulation,centrifugal pumping action and gravity.

Still another object of the invention is to provide an ovate tank with avolute impeller casing in the bottom of one end thereof, a tank floorwhich inclines downwardly toward the feed orifice of the casing and arelatively short, narrow, steep upwardly, inclined open trough fordirecting stock from the discharge orifice of the impeller casing to thetop of the inclined tank floor.

A still further object of the invention is to provide a pulping tankwith a narrow upwardly inclined open trough along one side thereof,close to the discharge orifice of a horizontally disposed, rotatingimpeller and a downwardly inclined floor occupying substantially theremainder of the tank bottom, thereby eliminating any midfeather andpermitting a stream of high velocity to penetrate beneath and alongsideanoppositely moving mass of paper stock.

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Other objects and advantages of the invention will be apparent from theclaims, the description of the drawings and from the drawings in whichFIG. 1 is a plan view of the apparatus of the invention.

FIG. 2 is a side elevation in section on line 2-2 of FIG. 1.

FIG. 3 is a side elevation in section on line 3-3 of FIG. 1.

FIG. 4 is an end elevation in section on line 4-4 of FIG. 1.

FIG. 5 is a view similar to FlG. 1 of a modification and FIG. 6 is aview similar to FIG. 2 of the modification shown in FIG. 5.

FIGS. 1-4 illustrate a preferred embodiment of the invention whichincludes the tank 26 having a side wall 21 of generally ovate outlinewith a small parti-circular end 22, a large parti-circular end 23 and apair of opposite straight sides 24 and 25.

Occupying nearly all of the area below the small end of tank 20 is thevolute impeller casing 26 which extends horizontally and preferablyoccupies about one-third of the area enclosed by the wall 2 1 of tank20. Impeller casing 26 has a flat, horizontal bottom plate 27 containingan annular pattern of perforations 28 leading to an annular dischargechamber 29 and a stock outlet 30. A flat horizontal top plate 32,forming a minor, but lowermost, portion of the tank bottom is spacedabove plate 27 and provided with a feed orifice 33 for feeding theimpeller 34 axially and downwardly. The casing side wall 35 is of voluteconfiguration with the axis of the impeller and the centre of orifice 33slightly offset from the longitudinal centre line of tank 20 whereby anaxial feed, peripheral discharge, centrifugal pump is formed.

A tangential, peripheral, discharge orifice 36 is provided in casing 26,the orifice being open at the top and approximately equal in width toone half the diameter of impeller 34, in order to maintain circulationat relatively high consistencies.

Ascending stock conduit means 37 is provided for directing pulped stockdischarged from orifice 36 toward the opposite larger end of tank 2@ andupwardly to a level well above the level of casing 26. Preferably means37 comprises an upwardly inclined trough 38 extending along the sidewall 25 and terminating within the large end of the tank 20 at 39.

As best shown in FIG. 3, trough 38 is entirely below floor level andshort, narrow and steep as compared to the remainder of the tank bottomfor receiving a high velocity stream of stock directly from the impellerthrough discharge orifice 36. The discharged stock is thus raised to alevel well above the level of the impeller 34, and of impeller casing26, while the stream is close to the impeller orifice and before it hasbeen substantially slowed by the inertia of the stock.

A tank floor 41 forms the major portion of the area of the bottom oftank 20 and extends laterally from the straight side wall 24 beyond thelongitudinal centre line of the tank over to the inner side wall 42 oftrough 38. Floor 4-1 commences at 43 well below the rim 44 of tank 2%and at a level well above the level of impeller casing 26. The floor 41inclines downwardly to merge along the transverse line 45, with the flattop plate 32 of casing 26.

The top plate 32 of casing 26 is cut away at 46 and an inclined plate 47extends from the bottom plate 27 upwardly to eliminate any vertical facein the path of stock discharge which might cause stapling oraccumulations of fibres. Plate 32 is preferably cut away at 48 when itjoins the side wall 25. I

The impeller 34 is mounted for rotation in a horizontal plane on avertical axis and is driven by the shaft 5a,

3 the impeller having vanes 51 for creating a vortex in the mass ofmaterial above casing 26 and discharging pulped stock peripherally andtangentially from orifice 36. The drive and the impeller are not new andare fully described in my prior Patents 2,351,492 and 2,557,174.

Preferably the outside diameter of the impeller 34 is about half thelength of the outside diameter of the casing 26 or about equal in lengthto the radius of the small parti-circular end 22 of wall 21. Preferablyalso, the length of the tank 20 is about two times the maximum diameterof the casing 26 while the height of the wall 21 of tank 20 is at leastas great as the maximum diameter of casing 26. V

With reference to the diameter of the impeller, the length of the tankis preferably between two and .four times such diameter and the heightof the tank is at least two times such diameter. The width of the tankis about two times such diameter and the total width of the dischargeorifices is about equal to one-half such diameter.

In operation the tank 20 is charged with a suitable quantity of waterand paper stock material such as old magazines and newspapers, up to thelevel of the dotted line shown in the drawing. The impeller is thenrotated counter clockwise, in the direction of the arrows, therebyforming a substantially vertical, vor'tical circulation which extendsfrom the upper level of the paper stock material downwardly to theimpeller 34. The entire small end of tank 20 is vortically affected withfloating debris rapidly submerged, moved through feed orifice 33 intocontact with impeller 34and thrown outwardly by centrifugal forcetherefrom while being pulped thereby. An eflluent stream of pulped stockis emitted through discharge opening 36 and guided upwardly along theside 25 or tank 20 to the level of the floor 41 at the large end 23 oftank 20. The discharge stream, in ascending trough 38, appliescirculatory force on the mass of material in the large end of the tankfrom below and from the outside to urge the mass back toward the smallend of the tank. The downwardly inclined floor 41 permits gravity toconstantly urge the mass toward the vortex and, of course, the pumpingaction of the impeller also tends to circulate the stock counterclockwise within the tank.

No midfeather, baflie or partition, above the level of the tank bottom,or floor, is required in the apparatus of the invention since all stocktends to flow by gravity toward the feed orifice of the impeller'casingfrom the far end the tank and the stream discharged up trough 38 makesits own penetration of the mass in the opposite direction until it alsotends to flow rearwardly by gravity toward the vortex. I have discoveredthat by locating the orifice 35, the plate 32 and the inclined plate 47as shown, there is a tendency of stock dischanged from the impeller toflow laterally across the tank before reaching the far end. I term thiscapability a hydraulic midfeather inasmuch as it tendsto merge theoutgoing stock with the stock returning to the vortex and therebyeliminates any'dead space in the tank.

The complete lopsided vortical circulation throughout the entire tankwith no dead, or cleavage area, between the outgoing and the returningstock becomes very noticeable as the consistency increases. It isachieved, by stock which rises from passage 38 while sufiicient flowextends to the end of the tank to maintain circulation.

It should be noted that the top line 43 of floor 41 and the terminalline 39 of trough 33 aregenerally at about the level of the mid heightof the vortex created by impeller 34. All material once submerged in thevortex and discharged by the impeller is delivered into the bottom ofthe mass of stock and tends to remain submerged thereafter as itrecirculates into the vertical action at the small end or" the tank;

In the device of this invention there is no tendency for the stock tocascade down into the impeller casing, the inclined floor causing thesmall end of the tank to be full height at all times. The rotation ofthe impeller is d at a predetermined speed, which may be about threethousand to six thousand feet per minute tip speed in the embodimentillustrated, which maintains circulation while also maintainingelfective vortical submer ence action. Thus at no time does the impellerrun bare of stock because of excessive angular speed or piling up of thestock in the far end of the tank.

In FIGS. 5 and 6 a modification is illustrated wherein an open tank 55of generally oval outline is provided, the tank 55 being undivided andfree of any partitions, bafiles, lobes or midfeathers above the level ofthe tank bottom, or flgir. The tank 55 includes the parti-circular endwalls 56 and 57 and the straight parallel side walls 58 and 5'9. Avolute impeller casing 60, impeller 61, impeller shaft 62 and axial feedorifice 63 are similar to those described above and constitute thevertical ci-rculation and defiberizing means 64 of the embodiment.However, the means 64 is located in the centre or" the bottom of thetank 55, below the level of the tank bottom, or floor rather than belowone end thereof. In addition, there are a pair of diametrically opposeddischarge orifices 67 and 68 each facing in the opposite direction andeach proximate one of the straight side walls 58 or 59.

A pair of opposite, open troughs 69 and 70- are provided each leadingfrom one of the orifices 67 or 6% along the adjacent side wall 58 or 59and around the adjacent end Wall 56 or 57 to about the centre thereof.Each trough 69 or 70 inclines upwardly to deliver the tangential,peripheral discharge of the impeller outwardly to the most remoteportions of the tank at a considerably higher level than that of thecasing. A pair of floors 71 and 72 incline outwardly from the end walls56 and 57 to the impeller casing to urge the stock inwardly to thevortex created above the feed orifice 63. Each trough 69 or 70 includesa suitable drain grating 73 or 74 for draining the contents of the tankafter defiberization.

In this application I use the term ovate to describe the outline, orplan, of the tank to distinguish from tanks, of circular outline. Thetank may be oval as in FIG. 5, or egg shaped as in FIG. 1 and theimpeller may be olfset from the longitudinal axis as in FIG. 1 or may becentred on the longitudinal axis as in FIG. 5. I use the term orifice todescribe the discharge mouth of the volute impeller casing of theinvention since the stock in the tank forms the top of the dischargepassage and creates a mouth-like aperture through which material isemitted.

I claim:

1. Apparatus for pulping and defibering paper stock comprising incombination a tank of ovate outline, a horizontal volute impeller casingbelow the level of the [door of said tank, said casing having an axialfeed orifice and at least one peripheral discharge orifice; a rotaryimpeller vwthin said casing creating a vortex above said feed orificeand discharging material longitudinally of said tank through saiddischarge orifice, a tank floor inclining downwardly toward the feedorifice of said casing and urging all stock in said tank into the vortexcreated by said impeller by gravity and relatively steep, short,ascending stock conduit means, below the level of said floor, connectingsaid discharge orifice with an end of said tank, said means directingthe peripheral discharge of said impeller initially upwardly to a levelwell above the level of said casing and impeller and into the area ofsaid tank most remote from said impeller casing, said tank being free ofmidfeather structure above said tank 2. A combination as specified inclaim 1 wherein said floor extends laterally from one side of said tanknearly to the other side thereof, constituting the'major portion 3. Acombination as specified in claim 1 wherein the length of said ovatetank is about four times the diameter of said impeller and the height ofthe wall of said tank is at least twice the diameter of said impeller.

4. A combination as specified in claim 1 wherein the width of thedischarge orifice of said casing is at least one-quarter the diameter ofthe impeller to assure circulation at consistencies above 5%.

5. A combination as specified in claim 1 wherein said ascending stockconduit means comprises an open trough inclining upwardly from saiddischarge orifice, along the adjacent side wall of said tank and arounda substantial portion of the adjacent end wall of said tank.

6. Apparatus for defibering paper stock comprising an elongated tankhaving a bottom, and side and end walls of generally ovate outline;vortical circulation and defiberizing means in the centre of the bottomof said tank, including a pair of diametrically opposed dischargeorifices each proximate the adjacent side wall of the tank; a pair ofupwardly inclined open, relatively steep, narrow troughs, below floorlevel on each opposite side of said tank, each leading from one of saiddischarge orifices, along the adjacent side wall to proximate the centreof the adjacent end wall of said tank and a floor in said tank,inclining downwardly from the opposite end walls thereof to saidvortical circulation and defiberizing means for urging paper stockdelivered by said troughs back into said means.

7. Apparatus for pulping and defiberizing paper stock comprising incombination a tank having an upstanding wall of generally ovate outlinewith opposite, particircular ends, and a pair of opposite straight sidesbetween said ends; a horizontal impeller casing extending between thestraight sides of said tank below the level of the tank bottom, saidcasing having a top plate with a constricted feed orifice therein andhaving a side wall of volute configuration with at least one dischargeorifice therein proximate one side wall of said tank; an impellermounted for rotation in a horizontal plane on a vertical axiswithin saidcasing said impeller being adapted to create a vortex thereabove whiledischarging stock peripherally at substantial speed through saiddischarge orifice, along the side wall adjacent thereto and toward theparticircular end wall in the path of said stock; a wide tank floorinclining downwardly from the wall of said tank to the top plate of saidimpeller casing, and a narrow trough inclining upwardly from the levelof said discharge orifice to floor level well above the level of saidfeed orifice, the eliluent discharge up said trough constituting ahydraulic midfeather and said tank being free of midfeathers, baffles orpartition above the level of the tank bottom.

8. In apparatus for defibering paper stock of the type having anelongated tank with an impeller rotatable on a vertical axis in a voluteimpeller casing below the level of the bottom of the tank, said casinghaving a horizontal top plate, with an axial feed orifice, forming thelowermost level of the tank bottom and having a peripheral dischargeorifice below said lowermost level, the combination of a dischargetrough upwardly inclined from the level of said discharge orifice, alongone side of said tank to proximate an end of said tank and terminatingat tank floor level and atank floor, entirely above the level of saidcasing, said floor inclining upwardly from the level of the top plate ofsaid casing tothe wall of said tank, said tank being free ofmidfeathers, partitions or baffies above the level of said tank floor.

9. Apparatus for pulping and defibering paper stock comprising anelongated tank having a bottom, a pair of opposite elongated side wallsand a pair of opposite curved end walls; a horizontally disposed, voluteimpeller casing extending between said opposite side walls, said casinghaving a horizontal top plate, with a central feed orifice, forming thelowermost portion of said tank bottom, an impeller mounted for rotationon a vertical axis within said casing below said feed orifice :and atleast one discharge orifice, below said top plate, for directingeffluent material peripherally and tangentially out of said casing,along .a side wall toward an end wall of said tank; a tank floorinclining upwardly at a predetermined angle from said top plate to thesaid end wall toward which said efiluent material is so directed, saidfloor constitnting the remainder of said tank bottom, and a troughextending from said discharge orifice along said side wall to thevicinity of the end wall toward which said effluent material isdirected, said trourgh being entirely below the level of said tank floorand inclining upwardly, at a greater angle than the angle of said floor,from discharge orifice level to well above said casing, at floor level.

References Cited in the file of this patent UNITED STATES PATENTS2,139,430 Witham Dec. 6, 1938 2,557,174 Cowles l June 19, 1951 2,641,971Ellis June 16, 1953 2,658,426 Cowles Nov. 10, 1953 2,703,533 Cowles Mar.8, 1955 2,707,420 Skardal et al. May 3, 1955 2,719,462 Fowler Oct. 4,1955 FOREIGN PATENTS Q 191,025 Switzerland Aug. 2, 19 37

